PNNL

Abstract

License renewal of existing nuclear power plants (NPPs) to extend operation from 40 to 60 to 80 years will require effective aging management programs for the 100’s of kilometers of electric power, control and instrumentation cables installed in each plant. Degradation of jacket, insulation and other cable components can reduce the ability of cables to withstand design-basis accidents. The groundwork for a research and development roadmap to address aging cable management in NPPs was laid at a July 2012 workshop1 that brought together subject matter experts from the U.S. Nuclear Regulatory Commission (NRC), the U.S. Department of Energy (DOE) national laboratories, the Electric Power Research Institute (EPRI), universities, and cable manufacturers and inspectors. The most common nondestructive evaluation (NDE) methods for gauging cable status include indentation and visual inspection. These methods are limited to evaluation of the surface easily accessed cable assemblies. Other current methods (such as time and frequency domain analysis, inductance and capacitance measurements, tan d, etc.) provide flaw detection, but are not predictive. The workshop identified the need to advance and develop new NDE methods to enable in-situ cable condition assessment. Key chemical, physical, and electrical indicators of cable aging with exposure to heat, radiation, moisture, chemicals, and mechanical stress need to be determined. Finally, models correlating the key cable indicators with NDE signals need to be developed that can aging cable remaining useful life.